334 



shown in fig. 1. From the exterior apex of each cone in the two distal 

 rows a tendinous cord extends to the interior apex of the following cone, 

 thus serving to hold the apices in position. The row most distant from 

 the axis has the deep part of the base of each cone firmly attached 

 to the outer half of a transverse process. That part of the base 

 distal from the axis is reflected to form an inscriptio 

 tendinea extending transversely to the mid-ventral 

 line. The superficial base of the cone blends with the fascial body 

 investment. That side of the base proximal to the axis is continued 

 forward as the distal side of a cone in the adjacent row. Therefore 

 it is seen that a transverse line through the apex of a cone in one 

 row will pass through the base of a cone in the adjacent row. 



In the middle row the deep sides of the bases are attached to 

 the post-zygapophyses and their spines. The distal and proximal sides 

 of the bases are continued as the lateral boundaries of cones in the 

 adjacent rows. The superficial sides of the bases have the same inser- 

 tions as those in the row previously described. The cones in the row 

 adjacent to the axis are somewhat flattened laterally by their close 

 apposition to the neural spines. The deep side of the base of each 

 cone is securely inserted on the postero-lateral division of the neural 

 spine. The distal side of each base takes the same course as the 

 corresponding side in the adjacent row. The proximal sides are fast- 

 ened to the neural spine and also to the fascia arising from the 

 neural spines to serve as the body investment. The superficial sides 

 of the bases and also one half of the superficial lateral boundaries of 

 the cones are blended with the external fascial envelope. The apices 

 of the cones in this row give off ribbon-like tendons which extend to 

 the interior of the following apices. Such is the general arrangement 

 of the cones in the superior dorsal mass. 



The size of these cones varies. Those of the distal row are all 

 of the same size and are somewhat larger than those of the other 

 two rows, the length being fully three centimeters and the diameter 

 of the base about one and a half centimeters. The length of a cone 

 in the middle row is two and a half centimeters while its base is less 

 than one centimeter. The length of a cone in the proximal row is 

 scarcely two centimeters, and its base is about one half a centimeter. 

 The preceding measurements were made on an animal almost one 

 metre long. 



Since the arrangement of these cones is so regular, it is easy to 

 estimate their number which I have calculated to be three hundred 

 and seventy two in the superior dorsal mass. 



